Start to flirt with her a lot. Show to her that you care about her and that you want to be her. This should be subtle but obvious enough that she would know. I can't exactly tell you how to do this because it is an art that you'll have to learn to master on your own. But experiment and see what works and what doesn't.
When you two are alone and not watched by people, start having deeper conversation. Ask her questions about herself and get to know her more. Do this several times if you can. Then one day when you're alone, tell her your feelings. Don't pressure her to say anything back or do anything. Just tell her how you feel and wait for her reaction. If she says that she likes you back, then yay! If she rejects you, then don't go off getting all mad. Be calm and say something like "okay, I understand. It's no problem." This will show that you are mature. And when you're alone, you can go ahead and cry or whatever it is you do when you're upset.
I hope things work out well for you. Good luck!
